JPS60187318A - Solvent regeneration method and apparatus - Google Patents

Abstract

To regenerate a physical solvent, loaded with sour gases, especially CO2 and H2S, the loaded solvent is treated with a stripping gas and/or is expanded to separate absorbed CO2 and the resultant solvent is subjected to thermal regeneration to desorb H2S. To reduce energy requirements during regeneration, the CO2 desorption is conducted on at least two different temperature levels, the second being for example 30 DEG -80 DEG C. higher than the first, with the first being conducted, e.g., at about those low temperatures conventional to low temperature absorption systems.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention aims at regenerating a physically acting solvent loaded with CO, H, and S in the vicinity of an acid gas.
A solvent regeneration device for stripping or expanding a loaded solvent with an I + pulling gas in order to separate the O2 and then heating the solvent in order to separate the absorbed H2S gas, and equipment therefor. It is related to.

[Conventional technology]

flk Hz S Fraktion When obtained by selective physical acid washing, H! S
The solvent loaded with C02 and C02 is treated with I(+1 in an inert gas, usually N8 gas, in a S enrichment column) to drive out most of the C02 and remove relatively soluble H
, S remaining in a solvent in small amounts has been known in the art. In the upper part of the column, H,S-enriched T(, 8) is simultaneously washed and recovered from the rising mixed gas by a H2S-free solvent.According to this method, at the top of the column, a The H,S-free residual gas is obtained and the H,S-containing solvent is removed from the reservoir.

From this H, S-containing solvent, HIS is removed by heating the reservoir in the next high-temperature regeneration tower in order to recover the H, S parts or regenerate the solvent. It is pulled out through the top.

It is theoretically possible to increase the H,8(D) concentration by increasing the amount of stripping gas and stripping more CO2.

However, it cannot actually be realized. This is because when the t of the stopping gas is increased, the amount of solvent at the top of the column for cleaning and recovering H and S also increases automatically, so more solvent must be treated at the bottom of the column. It is. Also, when the amount of stripping gas increases, CO
Since the amount of H and S stripped increases with 2,
The internal conversion of the column increases at the same time, resulting in H,S
The heat of solution for absorption becomes considerable in the cleaning recovery system.

As an alternative method for I(!El enrichment, a portion of the H!S fraction from the top of the high temperature regeneration tower is returned to the enrichment tower and this
It is also known to wash and recover H and S from the , 8 fractions. However, in this case, in order to highly enrich H, S, most of the top product must be returned to the high-temperature regeneration tower for H, S absorption; Also, the heat demand of the high temperature regenerator increases considerably due to cooling heat losses due to cleaning vapor-condensation, as well as cleaning vapor saturation of the return stream and multiple expulsions of CO3 and H,S.

If the nitrogen used as a stripping gas is e.g.
Partial oxidation of the containing charge is often limited by the design of the air cracker to obtain 02H!
Further concentration of the distillate fraction, S, has heretofore been required.

It is also known to concentrate H2S without using +1 Zbinda gas. Conventionally, in this case, the loaded solvent is expanded by means of a vacuum, with the C being removed by degassing.
The O snow reservoir is compressed to the pressure of the subsequent cleaning tower and treated there.

For this method, the pressure within the expansion vessel depends on the required H,S 9 degrees of the H,S portion. In particular, when the H and S contents in the crude gas are low or when it is desired to increase the Has distillate partial snow S concentration, in order to remove Co and distillate,
Being busy requires a large amount of energy consumption.

[Problem that the invention seeks to solve]

Therefore, it is an object of the present invention to reduce the energy consumption industry to a low level.
HiS fraction middle part! CO and H to increase S concentration
, S. The object of the present invention is to improve a regeneration method and apparatus for regenerating a solvent loaded with ,S.

[Means for solving problems]

This problem is solved according to the invention by carrying out the separation of CO2 at two different temperature levels.

In an attempt to increase the H,S concentration in the H,S reservoir while reducing energy consumption, we decided to perform the expulsion of CO at two different temperature levels compared to the conventional method described above. The inventor discovered that it was possible to increase the concentration of horse S more economically.

The gist of the present invention is that in regenerating the physically acting solvent loaded with acid gas, especially CO mushrooms and H,S, 1, in order to separate the absorbed CO2, CO2 and Hz S were loaded. In a solvent regeneration method in which the solvent is stripped or expanded with a stripping gas and then heated to separate the absorbed H, 8, Co1
This is a solvent regeneration method in which the separation of
a high-temperature regeneration tower to which the bottom of the H,S-enriched group is connected at the tip of the connecting conduit, and at least one heat exchanger disposed in the connecting pipe, The exchanger is a solvent regeneration device characterized in that the exchanger is connected to the storage section of the high-temperature regeneration tower through piping.

[Effect]

According to an advantageous embodiment of the regeneration process according to the invention, the solvent partially depleted of CO2 by stripping is warmed and treated with a stripping gas at an elevated temperature in order to separate off the majority of the CO2. Processed. In this case, it is desirable to warm the cold solvent from the partially stripped H,S enriched group by heat exchange with the regenerated solvent and then strip it with a stripping gas at an elevated temperature.

The inert gas required to strip dissolved gases from the liquid depends only on the solubility of the gas at constant pressure, which decreases with increasing temperature. Therefore, as the temperature rises, a smaller amount of stripping gas will melt the ico.

can be expelled. That is, a given ■ in acid gas! S.I.
I! The amount of stripping gas required to obtain 1 degree is less than for cold stripping. The gas 151E exiting the high temperature stripping area contains HmS in addition to Co1 depending on its solubility, so it must be washed secondary in the H, S enrichment column installed later. No.

Therefore, in the lower part of the first cold H,S enriched group, the main stream of CO, is first expelled, and then in the upper part of this column, the simultaneously expelled H, S-free solvent is removed. It is desirable to carry out the process so that it is washed and recovered. For this purpose, a portion of the stripping gas is fed into the lower part of this column.

After warming up the stripped solvent at low temperature, at an intermediate temperature preferably 60° to 80°C, especially 50 to 70°C higher, a small amount of stripping gas, especially the remaining amount of stripping gas used (total 50 of the amount of stripping gas
%, particularly in amounts of 10 to 30%) to further purge the remaining CO2f. The overhead product is led to the center of the cold stripping column where it is used together with the stripping gas for crude purification.

The division of the stripping tower into a relatively low temperature coarse stripping zone and a relatively high temperature finish stripping zone has the following advantageous effects. To remove CO2 from a loaded solvent by degassing, a certain amount of heat is required, which is extracted from the solvent and
Allow the solvent to cool.

In the cold coarse stripping zone, this cooling takes place at the temperature used in the preceding washing tower, thus saving external cooling heat. In hot stripping zones, on the other hand, cooling of the solvent at a relatively high temperature level can no longer be used to reduce the external cooling heat.

According to another embodiment of the regeneration process according to the invention, the solvent from which COl has been partially removed by expansion is further expanded, heated and led to a separator, where the CO2-containing gaseous fraction produced is After compression, the reservoir is optionally cooled by a condenser and led again to the first pressure stage, and the resulting liquid reservoir is led to H, S separation. According to this embodiment:
When using a separator after partial heating, CO2 due to expansion
Energy demand ftf can also be reduced in separation. In this case, it may be more economical to reduce the pressure below the enrichment tower pressure for the first expansion and compress the suction gas. As in the embodiment using a stripping gas, in this case too the temperature is preferably adjusted by heat exchange with the regenerated solvent, preferably from 60° to 80°C, in particular to 50°C.
The process is carried out at an elevated temperature of ~70°C.

According to the method of the present invention using a heated separator, a vacuum device and H
, the connection to the condenser can be omitted; the depressurization in the cold expansion vessel is carried out according to purely economic considerations, i.e. the cooling heat gain by degassing the loaded liquid and the degassed flash. This may be based on a comparison with the energy requirements for concentrating the vaporized gas and cooling it to the operating temperature of the secondary cleaning.

The present invention also includes an H,S enrichment tower, and a high-temperature regeneration tower in which the bottom of the H,S enrichment tower is connected at the tip of a connecting conduit.
A solvent regeneration device comprising at least one heat exchanger disposed in a skeleton connection conduit, the heat exchanger communicating with the storage section of the high temperature regeneration tower via piping. Also provided. Further, a stripping column or, alternatively, at least one separator is disposed in the connecting conduit, and the stripping column or the separator is connected to the H2S enrichment column via the column bottom, The top of the tower and the tower are connected to a high temperature regeneration tower via a reservoir.

In the regeneration method of the invention, the solvent used is any physically acting absorption liquid, especially an absorption liquid that is selective for H, S over CO2. These solvents include in particular alcohols such as methanol, ketones, N-methylpyrrolidone, dimethylformamide, polyethylene glycol ethers or aromatic compounds.

Next, the reproduction method of the present invention will be explained in detail based on the accompanying drawings.

〔Example〕

In FIG. 1, the H,S enrichment tower 6 is supplied with methanol loaded with CO at a rate of 60' from the previous washing step (not shown) through the pipe 1, and methanol loaded with HIS. Each is supplied through piping 2 at a rate of 40/h. The operating pressure of the H,S enrichment tower 6 is approximately 2.5 yen/
, 4 (2.4 bar). From the lower part of the H,S enrichment tower 6, a stripping gas such as horse gas having a temperature of 60° C. is supplied through a pipe 4f at a rate of 200 ON//h. The stripping gas rising inside the column drives out the CO2 absorbed in methanol and mainly removes CO, and N.
! The residual gas consisting of is discharged from the top of the column via pipe 5.

A part of HMS, which has high solubility in methanol, is also driven out by the stripping gas, so to prevent this, HIS is supplied to the top of the H,S enrichment tower 6 with CO! It is washed and recovered with methanol contained therein.

All the methanol supplied is increased at a temperature of -55°C from a pump 59fC via piping 6, and then transferred to -30°C through heat exchanger 2.
After being heated at 7, H! It is again supplied to the S enrichment tower 3. This operation further reduces the amount of CO remaining in methanol.
A portion of 2 is expelled from the methanol by this heating.

Reservoir 4 of HaS Futai Tower 3 from which CO mushrooms have been partially removed
The methanol of No. 6 is drawn off by a pump 69 through a pipe 7 at a temperature of -67°C, and heated to 64°C with regenerated methanol in a heat exchanger 8, that is, the H,S enrichment column feed liquid -
It is heated by 64° C. compared to 60° C., and is led to the upper part of the 20th H,S enrichment tower 9 (high temperature stripping tower). Second
Hz S enrichment tower 9 is approximately 2.8 g/cI! It operates at a pressure of i (2,7 bar). At the bottom of this second H,S enrichment tower 9, a stripping gas at a temperature of 60°C is supplied to the pipe 1 at a rate of 400 Nft//h.
It is supplied via 0. The supplied I + Zvinda gas contains CO snow and some H
, S are expelled, and Co, , N, and 25 Nyr at a temperature of 34°C are passed through the pipe 11 from the top of the second H,S enrichment tower 9.
? The residual gas with −8 /h is removed at a rate of 900”/h. This residual gas is led to the bottom of the H,S-enriched group 3 for washing and recovery of [(tS). In addition, the residual gas may be heated through a heat exchanger 8 and introduced into the lower part of the H, S-enriched group 3 in order to increase the Stritzbinder efficiency, as shown by the broken line.

From the pipe 12, the methanol in the storage section 46, which has been heated to 69 degrees Celsius compared to the methanol discharged from the base of the H2S enrichment tower at 62 degrees Celsius, from which most of the CO2 has been removed, is sent to the pump 6.
9, this methanol is heated to a high temperature of 102°C by a heat exchanger 16, and is heated to 8 by heat exchange with recycled methanol.
It is heated to 7° C. and guided to the upper part of the high temperature regeneration tower 14. The high temperature regeneration column 14 operates at a pressure of approximately 3.1 kg/i (3 bar), and the solvent in the reservoir 46 at the bottom of the column is heated by a power heater 15 heated by steam. H and S absorbed in methanol are expelled by heating the liquid in the storage section 46 and are drawn out from the top of the high temperature regeneration tower 14 via the arrangement pipe 16. The condensed methanol is completely cooled in the cooler 17 by the external cooling heat of 20,000 &lI/1, and is separated in the separator 18 and then internally e.g.
It is returned to the high temperature regeneration tower 14 through the pipe 19r, and the HzS28 moA
, % I (275Nn//h) is recovered via line 20 at a temperature of -65°C.

A part of the regenerated methanol at 102° C. from the storage section 46 of the high-temperature regeneration tower 14 is heated by the heater 15 as described above and returned to the storage section 46, and the remainder is sent via the pipe 21 to the pump 6? After being drawn out and cooled by heat exchangers 16 and 8, the cleaning process is repeated.

According to the regeneration method according to this example, compared to the conventional regeneration method under the same conditions except that the second FbS loaded tower (high temperature stripping tower) is not used, the regeneration method is 70,000-
/h of external cooling heat can be saved. This savings results, inter alia, from the reduction in the energy consumption of the external cooling heat required to cool down the hot column product of the regenerator 14 in the cooler 17.

According to FIG. 2, the solvent 60/h loaded with CO2 passes through the wind pipe 22 (not shown) in the previous stage of the cleaning process.
Further, the H2S-loaded solvent 40'/h passes through the pipe 26 and is expanded in the H,8-rich (t') column 24.

The internal force within the Has enrichment enrichment tower is about 2.1 to (2□Tvar). Due to the pressure drop, it is forced out of the co2Fi solvent, which has low solubility, and is drawn out from the top of the H,S-enriched group 24 via pipe 25. In order to prevent H and S from being expelled together, H and C were led to the top of Fuichi Tower 24.
02 Wash and recover H-S with the loaded solvent.

A pipe 26 is connected from the center of the H2S enrichment tower 24 via a pump.
After that, all the supplied solvent is withdrawn by a pump 69 at a temperature of -55°C, heated to -29°C in a heat exchanger 27, and then supplied to the H,S-enriched group 24 again. This heating further drives out some of the Co remaining in the solvent from the solvent.

From the piping 28, there is a storage section 4 from which CO is partially removed.
The solvent from 3 is drawn at a temperature of -29°C, approximately 0.4
The pressure is reduced to a pressure of kg/(0.4 bar) by a pressure reducing valve 29 and then led to a separator 60. Due to the degassing effect caused by this expansion, the contained CO2 is further removed, and this CO- is drawn out from the separator 60 via the pipe 31 as a gaseous reservoir, and is compressed by two-stage compressors 32a and 32b to about 1 .2
kV, 1 (1,2 bar), approximately 2.1 kg/
. Supplied. This gaseous reservoir (2475N/h)
contains Has 74”/h.

The methanol from separator 60, still containing COs and H,S, is at a temperature of -69°C, f? The regenerated solvent is drawn out by a pump 59Vc through a pipe 55, heated to 62°C by a heat exchanger 66, that is, by 61°C compared to the 29°C of the H,S-enriched column bottom, and then passed through another separator. 67. The pressure in the separator 67 is approximately 1.2 kV, [1.2 bar]
It is. This heating further drives out the CO contained, and this CO2 is drawn out from the separator 67 through one tube 5Bk as a gaseous reservoir (49 ON"/h, of which H and 8 are 31 N"/h). and about 2-1 at the compressor 32b.
kg/, 11 (2.1 bar) and, after being cooled by a cooler 66, is recycled to the H2S enrichment column 24.

The solvent methanol from which most of the CO2 has been removed is transferred to pipe 40.
is quietly drawn out from the separator 67 and transferred to the following high-temperature regeneration tower 1.
4 with a pump 42, during which time it is heated to 87°C with the regeneration solvent in the heat exchanger 41, and then transferred to the high temperature regeneration tower 1.
It is fed to the top of 4.

The high temperature regenerator 14 operates as described above in FIG. 1 and recovers the H2S fraction and the regenerated solvent free of H, S, and CO snow.

〔Effect of the invention〕

According to the solvent regeneration method and apparatus of the present invention, CO2 and H
CO2 and H, 8 can be efficiently separated from a solvent loaded with 2S, the amount of energy required for regeneration and solvent consumption can be significantly reduced compared to the conventional method, and it can be regenerated and recovered.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a regeneration apparatus according to an embodiment of the present invention using a stripping gas, and FIG. 2 is a process diagram showing a regeneration apparatus according to an embodiment of the invention without using a stripping gas. Explanation of symbols 3, 9. 24... H, S Fuichi Tower. 8.
13. 27. 36°41...Heat exchanger 014.
・Bengatsu Regeneration Tower. 15... Heater. 17.33・
··Cooler. 18.30.37...Separator, 32a,
32b, two-stage compressor. 39.42-i<ump, 46
...Reservoir 〇 Same symbols in the middle of the drawings indicate the same or the same functions. Daiokihito Patent Attorney Sanro Kimura

Claims (1)

[Claims] When regenerating physically active solvents loaded with acid gases, in particular CO2 and H,S, the loaded solvents are treated with a 11 Zbinda gas in order to separate the absorbed CO2. A method for regenerating a solvent by stripping or expanding and then heating the solvent to separate the absorbed HIS, characterized in that the separation of said C(h) is carried out at two different temperature levels. Regeneration method. (2) Heat the solvent from which CO has been partially removed by the above-mentioned step) +7 pipping treatment, and remove the solvent at a high temperature to remove most of the CO. 2. The method for regenerating a solvent according to claim 1, wherein the solvent regenerating method comprises: t31 The solvent regeneration method according to claim 2, characterized in that a small amount of pre-H piston stripper gas is used to remove most of the CO2. (4) Less than 50 inches, preferably 10 to 30 inches of the amount of stopping gas used for partial separation of COt + 1 topping gas, is added to COt.
O! The solvent regeneration method ε according to claim 6, characterized in that it is used to separate most of the solvent. (5) The solvent from which CO2 has been partially removed by the expansion is further expanded, heated, and guided to the separator, and depending on the amount of excess CO2O2-containing gas generated at that time, it is cooled after condensation, and then the solvent is reintroduced. The liquid portion H produced by leading to the pressure stage 1
, S separation. (61) The solvent regeneration method according to any one of claims 1 to 5, characterized in that the solvent from which CO2 has been partially removed is heated by heat exchange with the regenerated solvent. (7 ) Solvent from which CO was partially removed 'f-30~8
The solvent regeneration method according to any one of claims 1 to 6, characterized in that the temperature is preferably heated to 0°C, preferably 50 to 70°C. (8) In an apparatus for regenerating a physically acting solvent loaded with acid gas, in particular CO2 and H2S, an H2S enrichment column and the bottom of the H2S enrichment column are connected at the tip of the connecting conduit section. A high-temperature regeneration tower and at least one heat exchanger disposed in the connecting conduit, the heat exchanger being in communication with the high-temperature regeneration tower storage section via piping. Solvent regeneration equipment. (9) The solvent regeneration apparatus according to claim 8, characterized in that a stripping tower is disposed in the connecting conduit. II: At least one separator is disposed in the connecting pipe, and the separator is connected to the Hx8 enrichment tower via piping and to the high temperature regeneration tower via a storage section. 9. A solvent regeneration device according to claim 8. Claim 1, characterized in that a compressor and a cooler are disposed in the piping between the 0υ separator and the Has enrichment tower.
The solvent regeneration device according to item 0.